scholarly journals Low-carbon cast microalloyed steel intercritically heat-treated at different temperatures: microstructure and mechanical properties

2021 ◽  
Vol 21 (2) ◽  
Author(s):  
Hadi Torkamani ◽  
Shahram Raygan ◽  
Carlos Garcia Mateo ◽  
Yahya Palizdar ◽  
Jafar Rassizadehghani ◽  
...  
Keyword(s):  
Carbon Content ◽  
Volume Fraction ◽  
Block Size ◽  
Tensile Tests ◽  
Total Elongation ◽  
Martensite Phase ◽  
Low Carbon ◽  
Steel Increase ◽  
Different Temperatures ◽  
The Impact

AbstractIn this study, dual-phase (DP, ferrite + martensite) microstructures were obtained by performing intercritical heat treatments (IHT) at 750 and 800 °C followed by quenching. Decreasing the IHT temperature from 800 to 750 °C leads to: (i) a decrease in the volume fraction of austenite (martensite after quenching) from 0.68 to 0.36; (ii) ~ 100 °C decrease in martensite start temperature (Ms), mainly due to the higher carbon content of austenite and its smaller grains at 750 °C; (iii) a reduction in the block size of martensite from 1.9 to 1.2 μm as measured by EBSD. Having a higher carbon content and a finer block size, the localized microhardness of martensite islands increases from 380 HV (800 °C) to 504 HV (750 °C). Moreover, despite the different volume fractions of martensite obtained in DP microstructures, the hardness of the steels remained unchanged by changing the IHT temperature (~ 234 to 238 HV). Applying lower IHT temperature (lower fraction of martensite), the impact energy even decreased from 12 to 9 J due to the brittleness of the martensite phase. The results of the tensile tests indicate that by increasing the IHT temperature, the yield and ultimate tensile strengths of the DP steel increase from 493 to 770 MPa, and from 908 to 1080 MPa, respectively, while the total elongation decreases from 9.8 to 4.5%. In contrast to the normalized sample, formation of martensite in the DP steels could eliminate the yield point phenomenon in the tensile curves, as it generates free dislocations in adjacent ferrite.

Microstructure Development and Mechanical Properties of a Hot Stamped Low-Carbon Advanced High Strength Steel Treated by a Novel Dynamic Carbon Partitioning Process

2014 ◽  
Vol 1063 ◽  
pp. 42-46 ◽  
Author(s):  
Fei Bao Zhang ◽  
Hong Wu Song ◽  
Ming Cheng ◽  
Xin Li ◽  
Shi Hong Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Hot Stamping ◽  
High Strength ◽  
Carbon Partitioning ◽  
Martensite Phase ◽  
Low Carbon ◽  
Step Method ◽  
The Impact

To make steel exhibit attractive properties as high strength and good ductility, this paper presents a novel one step method for forming-Q&P integration—Hot Stamping-Dynamic Partitioning (HS-DP) process. The proposed HS-DP process is simulated with salt bath heat treatment. The effect of microstructure and mechanical properties in a low-carbon AHSS with different cooling rate of the new process is investigated by using scanning electron microscopy (SEM), X-ray diffraction (XRD) and tensile test methods. Microstructure of the steel subjected to HS-DP treatment is mainly composed of initial quenched martensite phase , final quenched martensite phase and retained austenite phase formed. The impact of retained austenite is also discussed, especially the influence of elongation caused by various retained austenite volume fraction and carbon-content. This experiment illustrates the promising application potential of the hot stamping-dynamic carbon partitioning process.

Experimental Investigations on the Influence of Temperature on the Behavior of Steel Reinforcement (Strands and Rebars)

2016 ◽  
Vol 711 ◽  
pp. 908-915
Author(s):  
Wiem Toumi Ajimi ◽  
Sylvain Chataigner ◽  
Yannick Falaise ◽  
Laurent Gaillet
Keyword(s):  
Prestressed Concrete ◽  
Temperature Increase ◽  
Mechanical Performance ◽  
Tensile Tests ◽  
Steel Reinforcement ◽  
Experimental Investigations ◽  
Tensile Behaviour ◽  
Nuclear Containment ◽  
Different Temperatures ◽  
The Impact

In the case of exceptional accidents, nuclear containment structures may be submitted to an internal temperature increase. This may have an influence on the prestressed concrete structures behavior regarding both its mechanical performance and its porosity. The presented study got interested on the impact that a temperature increase may have on the mechanical behavior of the steel reinforcement for both prestressing strands and rebars. In order to remain in realistic situations, it was chosen to study temperatures between 20°C and 140°C. Some experimental investigations regarding the tensile behaviour of steel rebars and their adherence within concrete will first be presented. Then, some investigations on steel strands will be described: some tensile tests at different temperatures, and some relaxation tests to check how the level of prestress loss may be affected by the temperature. This experimental study is part of a national French project (MACENA) aiming at assessing the impact of an accident on the behavior of nuclear containment structures. The gathered experimental data will be used for their damage assessment.

Microstructural Study of a High Bainite Dual Phase (HBDP) Steel Austempered at Different Temperatures

2010 ◽  
Vol 297-301 ◽  
pp. 62-67 ◽  
Author(s):  
R. Bakhtiari ◽  
A. Ekrami
Keyword(s):  
Impact Energy ◽  
Volume Fraction ◽  
Salt Bath ◽  
Total Elongation ◽  
Air Cooling ◽  
Dual Phase ◽  
Severe Reduction ◽  
Steel Bars ◽  
Different Temperatures ◽  
Austempering Temperature

4340 steel bars were austenitized at 850oC for 1 hour followed by heating at 700oC (ferrite and austenite region) for 90 min and quenching into a salt bath with different temperatures of 300, 350, 400 and 450oC. The steel bars were held for 1 hour at these temperatures before air cooling to room temperature. Various ferrite-bainite microstructures with 34% volume fraction of ferrite and different bainite morphologies were obtained. The results of SEM studies showed that by increasing the austempering temperature, the morphology of bainite varies from lower to upper bainite. According to the T-T-T diagram of the studied steel, the bainite transformation will not complete for the holding time of 1 hour at 400 and 450oC austempering temperatures and there can be 9 and 23Vol% of martensite at these temperatures respectively. Microstructural studies of specimens austempered at these temperatures showed complex microstructures of ferrite, bainite and martensite. Mechanical testing results showed reduction in yield and ultimate tensile strengths, hardness, uniform and total elongations and impact energy with increase of the austempering temperature from 300 to 400oC. But for dual phase steel austempered at 450oC, the yield and tensile strengths and hardness increased and a severe reduction in total elongation and impact energy was obtained. This brittle behaviour was related to martensite formation during cooling from this austempering temperature.

Deformation Behaviour of Martensite in a Low-Carbon Dual-Phase Steel

2006 ◽  
Vol 15-17 ◽  
pp. 774-779 ◽  
Author(s):  
M. Mazinani ◽  
Warren J. Poole
Keyword(s):  
Dual Phase Steel ◽  
Volume Fraction ◽  
Deformation Behaviour ◽  
Dual Phase ◽  
Low Carbon ◽  
Heating Rates ◽  
Dp Steel ◽  
Martensite Content ◽  
High Heating ◽  
Different Temperatures

The deformation behaviour of martensite and its effect on tensile properties of a lowcarbon dual-phase (DP) steel were investigated. DP steel samples with different martensite contents and morphologies were produced after intercritical annealing at different temperatures using low and high heating rates. Two distinct martensite morphologies were obtained for low and high heating rates. The investigated steel showed the unusual results that the true fracture stress and strain were found to increase with the martensite volume fraction. The plastic deformation of martensite was considered to be responsible for these results. Experimentally, it was observed that the martensite in DP steels with greater than 25-30% martensite can deform plastically during tensile straining. Finally, the effect of tempering on the martensite plasticity was also evaluated. It was found that the tempering process and an increase in the martensite content have a similar effect on promoting martensite plasticity.

scholarly journals Pengaruh Media Arang Kayu Bakau Mangrove Dan Arang Kayu Asam Pada Proses Perlakuan Carburizing Terhadap Sifat Mekanik Baja Karbon ST-37

2021 ◽  
Vol 12 (2) ◽  
pp. 30-37
Author(s):  
Rico Arifandi ◽  
Gerald Adityo Pohan
Keyword(s):  
Carbon Steel ◽  
Heating Temperature ◽  
Surface Hardness ◽  
Low Carbon Steel ◽  
Martensite Phase ◽  
Wood Charcoal ◽  
Holding Time ◽  
Low Carbon ◽  
Solid Media ◽  
The Impact

In the military field, tank is armored fighting vehicles that move using chain-shaped wheels. The tread of the tank chain is a component to tread and move so that it requires tougher properties on the surface and has ductile and tough properties on the inside and is more resistant to wear on the surface. The development of tank chain production materials is necessary for the independence of national defense and security as well as reducing dependence on imports. Imported tank chain hardness value 28 HRC or 286 HV. In this research, the objective of this research is to increase the surface hardness of the steel by carburizing the initial material, especially the low carbon steel ST-37. The carburizing treatment process is a method of adding carbon content in steel using solid media. The carbon media used were mangrove charcoal and tamarind wood charcoal using calcium carbonate (CaCO3) catalyst at a constant heating temperature of 900ºC, variations in holding time of 30 minutes, 60 minutes and 90 minutes, cooled rapidly with water media. Then performed an analysis of the effect of the type of wood charcoal on the mechanical properties of carbon steel ST-37. The results obtained will be applied to the tank chain tread production process. The results of the micro structure of martensite and the highest hardness value were found in the holding time of 60 minutes of mangrove charcoal media with the microstructure results of 63.8% martensite, 36.2% bainite and a hardness value of 453.1 HV. The highest toughness value is found in the holding time of 60 minutes of tamarind wood charcoal media with an impact price (HI) of 0.4345 J/mm2. The difference between the impact test results of tamarind charcoal media with mangroves is not too significant. The higher the martensite phase, the higher the hardness value. However, there is also a bainite phase which can increase the toughness of the steel which will be used as a tread chain production material.

Hot deformation behavior of low carbon advanced high strength steel (AHSS) microalloyed with boron

2009 ◽  
Vol 1243 ◽  
Author(s):  
I. Mejía ◽  
S. González-Sala ◽  
J.M. Cabrera
Keyword(s):  
High Temperature ◽  
Deformation Behavior ◽  
True Strain ◽  
High Strength ◽  
Tensile Tests ◽  
Strain Rates ◽  
Low Carbon ◽  
Compression Tests ◽  
Advanced High Strength Steel ◽  
Different Temperatures

ABSTRACTThis research work deals the influence of boron content on the high temperature deformation behavior of a low carbon advanced high strength steel (AHSS). For this purpose high temperature tensile and compression tests are carried out at different temperatures and constant true strain rates by using an Instron testing machine equipped with a radiant cylindrical furnace. Tensile tests are carried out at different temperatures (650, 750, 800, 900 and 1000°C) at a constant true strain rate of 0.001 s-1. Uniaxial hot compression tests are also performed over a wide range of temperatures (950, 1000, 1050 and 1100°C) and constant true strain rates (10-3, 10-2 and 10-1 s-1). In general, experimental results of hot tensile tests show an improvement of the hot ductility of the AHSS microalloyed with boron, although poor ductility at low temperatures (650 and 750°C). The fracture surfaces of the AHSS tested at temperatures showing the higher ductility (800, 900 and 1000°C) indicate that the fracture mode is a result of ductile failure, whereas in the region of poor ductility the fracture mode is of the ductile-brittle type failure. On the other hand, experimental results of hot compression tests show that both peak stress and peak strain tend to decrease in the AHSS microalloyed with boron, which indicates that boron generates a sort of solid solution softening effect in similar a way to other interstitial alloying elements in steel. Likewise, hot flow curves of the AHSS microalloyed with boron show an acceleration of the onset of dynamic recrystallization (DRX) and a delay of the recrystallization kinetics. Results are discussed in terms of boron segregation towards austenitic grain boundaries and second phase particles precipitation during plastic deformation and cooling.

Neutron Diffraction Analysis of Load Transfer in DP 600 Steel During In Situ Tensile Tests

2011 ◽  
Vol 681 ◽  
pp. 31-36
Author(s):  
Marc Seefeldt ◽  
Steven Dillien ◽  
Uwe Stuhr
Keyword(s):  
Neutron Diffraction ◽  
Inflection Point ◽  
Load Transfer ◽  
Volume Fraction ◽  
Tensile Tests ◽  
Martensite Phase ◽  
Lattice Plane ◽  
Hard Phase ◽  
Plastic Part

The load transfer among ferrite orientations and between ferrite and martensite was analysed in DP 600 steel by means of neutron diffraction duringin situtensile tests on the multiple pulse overlap time-of-flight strain scanner POLDI. The material had 0.07 wt% C and a martensite volume fraction of 15%.In situtests were done in “Young” as well as in “Poisson setup”. The martensite phase could not be probed due to its low tetragonality. The curves of the lattice plane strains as a function of the externally applied macroscopic stress reveal (1) plastic relaxations of transformation and intergranular stresses in the compliant <100> oriented grains, and (2) a second inflection point in the fully plastic part indicating the onset of plastic deformation of the hard phase.

Optimum Carbon Content for Tempered Martensitic Steels

1968 ◽  
Vol 90 (1) ◽  
pp. 1-7 ◽  
Author(s):  
J. D. Lubahn ◽  
H. P. Chu
Keyword(s):  
Carbon Steel ◽  
Carbon Content ◽  
High Carbon Steel ◽  
Low Carbon Steel ◽  
Tensile Tests ◽  
Notch Toughness ◽  
Low Carbon ◽  
Martensitic Steels ◽  
High Carbon ◽  
Engineering Concept

Notch-tensile tests were conducted on four quenched and tempered steels to study the effect of carbon content on notch toughness. The toughness was found to decrease when the carbon content was either above or below an optimum value of about 0.35 to 0.40 percent. The general engineering concept which prefers a low-carbon steel to a high-carbon steel for better toughness is briefly discussed in view of the present and previous experimental results.

Tensile Testing of Ti-6Al-4V Alloy Superplasticity

2013 ◽  
Vol 762 ◽  
pp. 392-397 ◽  
Author(s):  
Sergey A. Aksenov ◽  
Eugene N. Chumachenko ◽  
Irina V. Logashina
Keyword(s):  
Strain Rate ◽  
Material Flow ◽  
Flow Characteristics ◽  
Tensile Tests ◽  
Processing Maps ◽  
Dynamic Materials ◽  
Different Temperatures ◽  
Stress And Strain Rate ◽  
The Impact ◽  
Dynamic Materials Model

This paper presents the research on the flow characteristics of the Ti-6V-4Al alloy in wide ranges of temperature (725 ‑ 950 °C) and strain rate (10-5 ‑ 10-2 s-1). The material processing maps were constructed based on the basis of dynamic materials model (DMM) developed by Prassad and modified by Narayana Murty. For the construction of such maps the data of the material flow stress at different temperatures and strain rates is necessary. To obtain such data the stepped tensile tests which allow obtaining the stress - strain rate dependence at a given temperature are ideal. The experiments conducted consist of the tensile test series at various temperatures with stepped change of the deformation rate. By the results of these tests the constitutive equations, which describe relationship between stress and strain rate for each temperature, were obtained. The data was analyzed in terms of the two different approaches proposed by Prassad and Narayana Murty to assess the impact of deformation conditions on the formability and flow stability of the material. Based on these approaches, the processing maps, which enable identifying the conditions of the Ti-6V-4Al alloy superplasticity, were constructed.

scholarly journals Microstructural and Mechanical Evaluations of SAW By Manufactured Granular Basic Bonded Cr, Mo, and Cr-Mo Active Fluxes on ST37 Low Carbon Steel

2021 ◽  
Author(s):  
Mahdi Alishavandi ◽  
Mahdi Mohammadmirzaei ◽  
Mahnam Ebadi ◽  
Amir Hossein Kokabi
Keyword(s):  
Arc Welding ◽  
Volume Fraction ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Number Density ◽  
Longitudinal Tensile Strength ◽  
The Impact ◽  
St37 Steel ◽  
Submerged Arc ◽  
Bonded Method

Abstract Bead-on-plate submerged arc welding was conducted on St37 steel by manufactured Cr, Mo, and Cr-Mo active basic fluxes produced via the unfused bonded method. The base metal heat-affected zone and weld metal (WM) microstructures were identified and characterized by optical microscopy and scanning electron microscopy. Then, the ferrite morphologies volume fraction of WMs were measured. Moreover, the chemical analysis of slag and inclusions was evaluated by point scan energy-dispersive X-ray spectroscopy and extensively discussed. Inclusions number density and size and their effects on the formation of AF were also elaborated. Then, the WMs’ longitudinal tensile strength and Vickers hardness were measured. Finally, the Charpy V-notch test was conducted to determine the impact toughness; the fracture surfaces were investigated, as well.

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